Catalytic Converter for Honda Civic Si (2012-2015) 2.4L

Direct-Fit Exhaust Manifold Catalytic Converter for 2012-2015 Honda Civic Si (FB6/FG4)

What it Does: This direct-fit exhaust manifold catalytic converter bolts directly to the cylinder head on 2012-2015 Honda Civic Si (FB6/FG4) models with the K24Z7 2.4L engine to restore exhaust flow, eliminate catalyst efficiency fault codes, and convert HC, CO, and NOx emissions.

The Stock Honda Civic Exhaust Manifold Failure

On the FB6/FG4 Civic Si equipped with the K24Z7 2.4L engine, the factory catalytic converter is integrated directly into the exhaust manifold at the cylinder head. Positioned inches from the exhaust ports, extreme thermal cycling and heat soak cause the OEM ceramic honeycomb to fracture or poison over high mileage. As the precious-metal washcoat degrades, oxygen storage capacity drops and triggers P0420 or P0430 faults. A broken internal brick also rattles under deceleration and restricts exhaust gas scavenging.

Common Symptoms of a Failing OEM Catalytic Converter

• Check Engine Light / DTCs: Triggers P0420 or P0430 when post-catalyst oxygen sensor readings mirror upstream exhaust fluctuations due to depleted washcoat efficiency.
• Metallic Exhaust Rattle: Fractured internal ceramic substrate pieces vibrate inside the manifold housing, particularly during cold starts or off-throttle deceleration.
• Sluggish Acceleration & Failed Emissions: Dislodged honeycomb chunks create severe exhaust backpressure, choking top-end K24Z7 power while failing federal tailpipe inspections.

The Direct-Fit Stainless Exhaust Manifold Solution

This one-piece exhaust manifold catalytic converter replaces the failed OEM assembly using a corrosion-resistant stainless steel body and tubular runners engineered to withstand cylinder-head heat. Inside the 8-inch by 5-inch canister, a high-flow ceramic honeycomb substrate treated with a precious-metal washcoat restores proper HC, CO, and NOx conversion for OBD-II compliance. Precision-stamped head flanges, a factory-style downstream outlet, and integrated pre- and post-catalyst oxygen sensor bungs ensure leak-free sealing without cutting or welding.

What's Included

• 1 x Direct-Fit Exhaust Manifold Catalytic Converter Assembly
• 1 x Exhaust Manifold Gasket

Technical Specifications

Compatibility

• Make: Honda
• Model: Honda Civic Si 2.4L (Coupe and Sedan)
• Years: 2012, 2013, 2014, 2015
• Engine: 2.4L I4 (K24Z7)
• Exclusions: Does NOT fit Civic 1.8L, Hybrid, or Natural Gas models
• Emissions Notice: EPA (Federal) compliant only; NOT CARB approved and not legal for vehicles registered in California, New York, Colorado, or Maine

Frequently Asked Questions & Fitment Warnings

Does this fit the FB6/FG4 Civic?

Yes. This is a direct fit for the 2012-2015 Honda Civic Si (FB6 sedan and FG4 coupe) equipped with the K24Z7 2.4L engine. It does not fit Civic 1.8L, Hybrid, or Natural Gas models, and this EPA federal converter is not CARB approved for vehicles registered in California, New York, Colorado, or Maine.

Will this clear P0420/P0430 codes, and are O2 sensors included?

Yes, it clears catalyst efficiency codes caused by a failed converter, though oxygen sensors are not included. Transfer your existing pre- and post-cat sensors or install new units, and verify there are no upstream exhaust leaks that could trigger P0420 or P0430.

Are gaskets included, and what installation prep is required?

Yes, a new exhaust manifold gasket is included for the cylinder head flange. Let the exhaust cool completely, soak the factory fasteners in penetrating oil prior to removal, and torque all manifold nuts evenly before checking every joint for leaks.

The Honda Performance Standard

Restoring unrestricted exhaust scavenging on the high-revving K24Z7 keeps VTEC crossover crisp and eliminates backpressure loss across the powerband. Built for daily-driven durability and accurate OBD-II readiness, this direct-fit assembly returns your FB6/FG4 Civic Si to factory flow efficiency and throttle response.